Joist hangers are used in building construction to secure the ends of joists or other members to headers or other support members. Typically, the joist hanger includes a u-shaped portion that receives the joist. The bottom surface of the joist rests on the seat of the hanger, and the side walls of the hanger are dimensioned to closely receive the side faces of the joist, providing it with lateral support.
Where appropriate, the joist may be connected to the hanger by means of nails driven through the side walls into the side faces of the joist. These nails may simply be driven horizontally into the joist, in which case they are preferably short nails that will not pass through the joist. Alternatively, longer nails may be used that are driven horizontally and angularly into the joist such that they are driven into the header as well. This is commonly referred to as toe-nailing. The other common way to nail the hanger to the joist is to use short nails that are driven downward at an angle into the joist only.
Often, in order to connect the joist hanger to the header, back flanges are attached to the side walls. Generally, these flanges extend laterally from the side walls, to overlap a portion of the face of the header. These flanges can extend inwardly or outwardly from the side walls, depending on design considerations.
Openings may be provided in the back flanges to receive fasteners. These fasteners are generally nails in light-frame wood construction. Screws and bolts are also used in wood construction, depending on the size of the members to be joined and other considerations. In light-gauge steel construction, sheet metal screws, bolts and rivets are commonly used.
In perhaps the simplest hangers, the back flanges extend outwardly from the side flanges, providing an easily-accessed fastening face. Fasteners are then driven though the back flanges into the header. In other instances, design considerations dictate which particular attachment method is used for attaching the joist and the hanger to the header.
In addition, top flanges may be attached to the back flanges to aid in attaching the hanger to the header. Hangers with top flanges are generally referred to as top-flange hangers. Hangers without top flanges are generally referred to as face-mount hangers. If the top flanges wrap over the top of the header and down the back of the hanger can be called a wrap-around hanger. Again, various design considerations dictate what features are present in a hanger, and various building considerations dictate which hanger, or type of hanger, is used in a particular situation. Generally, if a top flange is used and the header is made of wood, pre-formed holes with be provided in the top flanges to receive suitable fasteners for connecting the top flange to the hanger. No such fastener openings are required in steel construction because the hanger is typically fastened to the header with self-drilling sheet metal screws or by welding.
As mentioned above, it is often desirable to fasten the joist to the hanger. This is generally done to resist uplift forces acting on the joist. Such forces are often caused by lateral loading on the building due to high winds or seismic activity. Also, one end of a joist must be downwardly restrained if that joist is cantilevered (e.g., to support an overhanging deck). As mentioned above, openings may be provided in the side walls of the hanger so that the joist can be held down with fasteners driven through the openings and into the joist.
Drywall is used in barriers, but generally cannot be used to shield supporting structural members like top plates and headers because drywall is susceptible to cracking and crushing and has little bearing strength with regard to fasteners in the drywall. The present invention allows drywall to be applied to the supporting structural members, shielding them, and provides a joist hanger connection that does not damage the drywall. Importantly, the present invention does not require any alteration of the drywall or the addition of any otherwise extraneous components. The drywall can simply be applied to the front face of the supporting member, completing covering and shielding it, and the joist hanger can then be attached by driving long screws directly through the drywall and into the supporting structural member.
The present invention uses sufficiently long, thick and stiff screws that the screws can act as cooperating cantilevers, holding the hanger away from the header and against the first drywall panel without sagging. The hanger applies a sufficiently large, flat surface to the exterior drywall sheet in order to stabilize the connection without crushing the drywall either during installation (when the screws might otherwise be overdriven) or after.